Atomic Force Microscope Tip Calibration Using Batog Model

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Solution Overview

Problem

Current methods for calibrating atomic force microscope tips are inefficient and inaccurate due to the lack of a generally accepted method for accounting for the specific geometry of the tip, often requiring multiple reference samples and literature values to support results.

Innovation Solution

A method that records a stiffness-force curve on a reference sample with known mechanical properties, uses the Batog model to account for tip geometry and surface unevenness, and performs a compensation calculation to determine the tip radius and stiffness, allowing for precise calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If existing calibration methods are used that disregard tip geometry, then calibration can be performed without complex models, but calibration accuracy deteriorates due to errors from ignoring specific tip geometry

Engineering Contradiction:
Improveease of calibrationVSAvoidcalibration accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent transforms the calibration approach by changing the mathematical parameters used to describe tip-sample interaction. Instead of using simple geometric models, it employs a stiffness-force curve analysis with reciprocal stiffness transformation, allowing accurate determination of tip radius and stiffness without requiring precise geometric assumptions about the tip shape

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary reference sample with known mechanical properties as a mediator between the tip and unknown samples. By first calibrating the tip stiffness using the reference sample's known reduced elastic modulus, the system creates a reliable baseline that accounts for actual tip geometry effects, which then serves as the foundation for measuring unknown samples

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If multiple reference samples and literature values are required for calibration, then calibration accuracy may be improved, but calibration time and complexity increase

Engineering Contradiction:
Improvecalibration accuracyVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts and isolates the essential calibration information from a single reference sample by measuring the stiffness-force curve and applying the reciprocal stiffness transformation. This extraction process captures all necessary tip geometry effects in one measurement, eliminating the need to use multiple reference samples or consult literature values for calibration support

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary calibration action by determining the tip stiffness and radius using the reference sample before measuring unknown samples. This preliminary characterization of the tip's actual mechanical properties accounts for geometry effects in advance, enabling accurate subsequent measurements without requiring additional calibration steps

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate and time-efficient calibration of atomic force microscope tips, providing reliable measurements for samples with unknown mechanical properties by accounting for tip geometry and surface roughness.

Implementation Method 1

a stiffness-force curve of a reference sample with known mechanical properties is first recorded with the tip to be calibrated

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3602081B1Method of calibration of a tip of an atomic force microscope
Publication Date: 2023.10.18 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3602081B1 patent drawingFigure 1~3
  • EP3602081B1 patent drawingFigure 4~5
  • EP3602081B1 patent drawingFigure 6~7

AI summary

The invention relates to a method for calibrating the tip (1) of a scanning force microscope, in which, firstly, a stiffness-force curve (k*(F)) of a reference sample (2) having known mechanical properties is recorded by means of the tip (1) to be calibrated. Then, the reciprocal (1/k*(F) of the stiffness-force curve (k*(F)) is formed, wherein the reciprocal (1/k*(F)) is formed as a sum of the reciprocal of the stiffness (K) following the Batog model and a further reciprocal of the stiffness (kma), which depends on surface irregularities of the tip (1). A compensatory calculation is created with the reciprocal of the recorded stiffness-force curve (1/k*(F)) having the stiffness (K) following the Batog model and a pre-factor (B), in which the reciprocal of the stiffness (kma), which depends on surface irregularities of the chip (1), is incorporated, is created as a parameter, and then a radius of the chip (1) and the tip stiffness (ktip) is calculated.